Determining Drainage Constraints and Geometries in a Triangular Mesh

1. A computer-implemented method for designing a terrain surface, comprising: (a) obtaining, in a computer, a triangular surface mesh representative of an existing surface, wherein the triangular surface mesh comprises two or more triangles that are connected by vertices and edges; (b) specifying a drain intention for the terrain surface through one or more geometries, wherein: (i) each of the one or more geometries comprises a point or a line; and (ii) the drain intention defines a drainage flow that influences a shape of the terrain surface; (c) modifying the triangular surface mesh based on the drain intention resulting in a modified triangular surface mesh, wherein: (i) the modifying is based on the one or more geometries; and (ii) the modifying prevents a drain conflict between the two or more triangles; (d) autonomously determining a drain direction of each of the two or more triangles in the modified triangular surface mesh based on the drain intention, wherein the autonomously determining generates a drain pattern that is used to shape the terrain surface.

2. The computer-implemented method of claim 1, wherein specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a low point.

3. The computer-implemented method of claim 1, wherein specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a drain line.

4. The computer-implemented method of claim 1, wherein specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a ridge line.

5. The computer-implemented method of claim 1, wherein autonomously determining the drain direction of each triangle comprises: determining a geometry direction to a nearest geometry of the one or more geometries; determining the drain direction based on the geometry direction and a drain intention type of the nearest geometry.

6. The computer-implemented method of claim 1, wherein autonomously determining the drain direction of each triangle comprises: identifying one or more zones, wherein each of the one or more zones include a subset of the one or more geometries; selecting one of the one or more zones; determining a geometry direction to a nearest geometry, of the one or more geometries within the selected zone; and determining the drain direction based on the geometry direction and a drain intention type of the nearest geometry.

7. The computer-implemented method of claim 1, further comprising: identifying one or more zones of the triangular surface mesh; selecting one of the one or more zones; determining a geometry direction of the selected zone; and determining the drain direction based on the geometry direction, wherein the drain direction complies with a minimum slope constraint.

8. The computer-implemented method of claim 1, further comprising resolving the drain conflict between the triangles by: creating a Voronoi diagram of the terrain surface using the one or more geometries, wherein: the Voronoi diagram comprises an advanced Voronoi diagram; the advanced Voronoi diagram is based on lines or curves; the Voronoi diagram comprises one or more Voronoi cells; placing a surface mesh break line along borders of the one or more Voronoi cells in the Voronoi diagram; and retriangulating the triangular surface mesh along the placed break lines to result in the modified triangular surface mesh.

9. The computer-implemented method of claim 1, further comprising: identifying a first zone and a second zone of the triangular surface mesh, wherein the first zone overlaps with the second zone; defining a hierarchy for the first zone and the second zone, wherein: the first zone is higher priority than the second zone; settings of the first zone override settings of the second zone; determining a first geometry direction of the first zone and a second geometry direction of the second zone based on the hierarchy; and determining the drain direction of each of the two or more triangles based on the first geometry direction and the second geometry direction.

10. The computer-implemented method of claim 1, further comprising: building the terrain surface based on the drain pattern.

11. A computer-implemented system for designing a terrain surface, comprising: (a) a computer having a memory; (b) a processor executing on the computer; (c) the memory storing a set of instructions, wherein the set of instructions, when executed by the processor cause the processor to perform operations comprising: (i) obtaining a triangular surface mesh representative of an existing surface, wherein the triangular surface mesh comprises two or more triangles that are connected by vertices and edges; (ii) specifying a drain intention for the terrain surface through one or more geometries, wherein: (1) each of the one or more geometries comprises a point or a line; and (2) the drain intention defines a drainage flow that influences a shape of the terrain surface; (iii) modifying the triangular surface mesh based on the drain intention resulting in a modified triangular surface mesh, wherein: (1) the modifying is based on the one or more geometries; and (2) the modifying prevents a drain conflict between the two or more triangles; (iv) autonomously determining a drain direction of each of the two or more triangles in the modified triangular surface mesh based on the drain intention, wherein the autonomously determining generates a drain pattern that is used to shape the terrain surface.

12. The computer-implemented system of claim 11, wherein the operations specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a low point.

13. The computer-implemented system of claim 11, wherein the operations specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a drain line.

14. The computer-implemented system of claim 11, wherein the operations specifying the drain intention comprises: specifying a drain element type for one of the one or more geometries, wherein the drain element type comprises a ridge line.

15. The computer-implemented system of claim 11, wherein the operations autonomously determining the drain direction of each triangle comprises: determining a geometry direction to a nearest geometry of the one or more geometries; determining the drain direction based on the geometry direction and a drain intention type of the nearest geometry.

16. The computer-implemented system of claim 11, wherein the operations autonomously determining the drain direction of each triangle comprises: identifying one or more zones, wherein each of the one or more zones include a subset of the one or more geometries; selecting one of the one or more zones; determining a geometry direction to a nearest geometry, of the one or more geometries within the selected zone; and determining the drain direction based on the geometry direction and a drain intention type of the nearest geometry.

17. The computer-implemented system of claim 11, wherein the operations further comprise: identifying one or more zones of the triangular surface mesh; selecting one of the one or more zones; determining a geometry direction of the selected zone; and determining the drain direction based on the geometry direction, wherein the drain direction complies with a minimum slope constraint.

18. The computer-implemented system of claim 11, wherein the operations further comprise resolving the drain conflict between the triangles by: creating a Voronoi diagram of the terrain surface using the one or more geometries, wherein: the Voronoi diagram comprises an advanced Voronoi diagram; the advanced Voronoi diagram is based on lines or curves; the Voronoi diagram comprises one or more Voronoi cells; placing a surface mesh break line along borders of the one or more Voronoi cells in the Voronoi diagram; and retriangulating the triangular surface mesh along the placed break lines to result in the modified triangular surface mesh.

19. The computer-implemented system of claim 11, wherein the operations further comprise: identifying a first zone and a second zone of the triangular surface mesh, wherein the first zone overlaps with the second zone; defining a hierarchy for the first zone and the second zone, wherein: the first zone is higher priority than the second zone; settings of the first zone override settings of the second zone; determining a first geometry direction of the first zone and a second geometry direction of the second zone based on the hierarchy; and determining the drain direction of each of the two or more triangles based on the first geometry direction and the second geometry direction.

20. The computer-implemented system of claim 11, further comprising: building the terrain surface based on the drain pattern.